Disk Brakes???

I have a set of the stock 4 piston calipers from a 72 Duster with the small 4" bolt pattern and power asist. Will these calipers work properly on the larger 4.5" bolt patern disk brakes or will the 4.5" rotors be too big in diameter for these calipers to work? Since these are 4 piston performance calipers it would be great to be able to use these so I won't have to spend money on an aftermarket setup or search for the stock replacements.